Many buildings and other structures such as concrete structures are aging rapidly. Consequently, it has become increasingly important to determine and monitor the structural integrity of these structures. Systems and methods for testing structures such as concrete structures are slow, tedious, dangerous and expensive. The present disclosure relates to improved detection and analysis of faults, such as debonded cladding, deteriorating structural components, and failure in structures, including concrete structures and other structures, where such faults are located through use of non-contacting interrogation of the structure by a remotely controlled device equipped with an interrogation system.
Structures such as building facades, building structures, dams, bridges, power plants and off-shore platforms have failure modes that include delamination, debonding, connection failures, and cracking, as well as deterioration from fatigue, over stressing and ambient exposure. In addition to failure in service, these materials may also suffer from defects in manufacturing similar to those which occur under field stresses. Thus, a practical technique is needed for non-destructively locating faults in composite structures which is suitable to safely and cost effectively evaluate structures in the field.
Among known techniques for detecting delamination or debonding is that known as acoustic “scrubbing” wherein a small instrument containing an acoustic crystal is manually scanned across the object under examination through contact with the surface object while electronically “listening” for anomalies in the reflected acoustic wave. For small objects, this process is simple and efficient, but is much too time-consuming, and therefore prohibitively expensive, to be practical for evaluation of large components and structures.
Other techniques for locating faults in concrete structures involve either tapping on the surface of the structure with a hammer at different spots or dragging a chain bar across the surface of the structure. A sharp or ringing sound is produced by an intact, healthy structure. However, where a fault exists, a dull hollow sound is heard. These techniques have the advantage of being simple and inexpensive. However, while these techniques allow inspectors to inspect large structures in a shorter amount of time than is possible with some other nondestructive testing techniques, such as acoustic/ultrasonic methods, they are still very time-consuming. In addition, these techniques have the disadvantages of (a) relying on the subjective interpretation of the inspector; and (b) being difficult to implement in noisy environments, such as inspecting one lane of a bridge deck while traffic is driving in the other lanes. These disadvantages make it impractical for evaluation of most structures. These prior art techniques also require either physical contact between sensors and the surface to be tested, or at least close proximity between the two. These sound-based techniques also require physical access which is further time consuming, expensive and dangerous, requiring special-purpose scaffolding and equipment and highly-trained operators.
Alternative prior art techniques rely on systems that incorporate sonic/ultrasonic inspection technology (see, e.g., www.ndtcorporation.com/en/capabilities/sonic-ultrasonic-inspection) or ground penetrating radar inspection technology (see, e.g., www.ndtcorporation.com/en/capabilities/ground-penetrating-radar). These prior art techniques also require either physical contact between heavy hand-held equipment and the surface to be tested, or at least proximity between the two. Such contact or close proximity requirements prove to be a disadvantage when it is desired to conduct testing of an external structure, side-wall of a building, bridge, or other structures, which are at a high elevation or in an area with difficult accessibility.
Therefore, in view of these disadvantages, there is a need in the art for an improved system and method to detect and record structural (and other) faults in and on structures.